The present invention relates to sound detecting devices commonly utilized for burglar alarms or other types of intrusion alarms where the device is designed to detect, for example the sound of breaking glass, or sounds characteristic of forced entry or other sounds characteristic of a selected incident.
Heretofore the adjustment of such devices, particularly sound discriminating devices, activated by certain selected sounds has been accomplished by trial and error methods where the sensitivity of the unit has been adjusted to actuate on occurence of the selected incident. No test unit is known in the prior art to determine the relationship between the activation level of the sound discrimination detector device and the characteristics of background noise to assist in adjusting the sensitivity of the device.
More particularly, the prior art provides no known method of assessment of the environment in which the detector is located before actual usage so the prior art devices are subject to false tripping by background noise if sensitivity is too high. Likewise if sensitivity is too low the unit does not detect the desired occurance.
Accordingly, it has been found that use of an indicator device in accordance with the present invention provides enhanced selectivity and reliability of an alarm system.